To address the rising need for cell assays in drug discovery, we propose a method for the rapid and simple generation of cell arrays by incorporating a novel transfection method into our current cell array technology. Our technology platform uses encoded microcarriers to multiplex pre-established cell types for simultaneous interrogation in a single microtiter well. We propose to combine our platform with a method of "reverse transfection" in which cells become transfected with material pre-deposited on a substrate. Specifically, we propose to use the carriers to deliver transfection material to cells plated on top of them. This approach would enable drug discovery laboratories to perform cell assays in a multiplexed manner, thereby decreasing the time, labor and reagent use involved with these assays as well as increasing the quality of data obtained from them. In addition, using reverse transfection to generate cell arrays substantially decreases the tissue culture burden associated with traditional transfection by alleviating the need for separate transfections and stable cell lines. We have obtained preliminary data supporting the technical feasibility of reverse transfection using encoded carriers. In this proposal, we outline a strategy for optimizing this approach and testing its feasibility for use in multiplexed cell assays. [unreadable] [unreadable]